Sensor and method for manufacturing the same

Abstract

Provided is a sensor having a high sensitivity and a high degree of freedom of layout by reducing constrictions of the channel shape, the reaction field area, and the position. Provided is also a method for manufacturing the sensor. The sensor ( 10 ) includes: a source electrode ( 15 ), a drain electrode, ( 14 ), and a gate electrode ( 13 ) arranged on silicon oxide film ( 12 a , 12 b ); a channel ( 16 ) arranged on the silicon oxide films ( 12 a , 12 b ) and electrically connected to the source electrode ( 15 ) and the drain electrode ( 14 ); and a reaction field ( 20 ) arranged on the silicon oxide films ( 12 a , 12 b ). The reaction field ( 20 ) is formed at a position on the silicon oxide film ( 12 a ), the position being different from a position for the channel ( 16 ). With this configuration, it is possible to independently select the shape of the channel ( 16 ) and the area of the reaction field ( 20 ). This enables the sensor ( 10 ) to have a high measurement sensitivity and a high degree of freedom of layout.

The invention claimed is: 
     
       1. A sensor comprising:
 a silicon substrate having a silicon oxide film; 
 a source electrode and a drain electrode, the source electrode and the drain electrode being arranged on the silicon oxide film; 
 a channel being arranged on the silicon oxide film and being electrically connected to the source electrode and drain electrode; 
 a reaction field having a thickness and being located on the silicon oxide film; 
 a barrier section surrounding the reaction field and being thicker than the reaction field, the barrier section formed of an insulating material; and 
 a gate electrode being arranged on the barrier section; 
 wherein the source electrode and the drain electrode are arranged on a different place from the reaction field. 
 
     
     
       2. The sensor according to  claim 1 , wherein the reaction field is surrounded by the gate electrode. 
     
     
       3. The sensor according to  claim 1 , wherein the barrier section is formed of silicon oxide. 
     
     
       4. The sensor according to  claim 1 , wherein the channel is a poly-silicon film or amorphous silicon film. 
     
     
       5. The sensor according to  claim 1 , wherein:
 the silicon substrate has the silicon oxide film on either or both surfaces; and 
 the reaction field, the source electrode, the drain electrode and the channel are arranged on the same silicon oxide film. 
 
     
     
       6. A method for manufacturing a sensor that includes a field effect transistor having a semiconductor substrate, a silicon oxide film formed on a surface of the semiconductor substrate, and an electrode connected to the silicon oxide film, part of the silicon oxide film being a reaction field for a detection target substance, the method comprising:
 forming a silicon oxide film on a silicon substrate; 
 forming a channel on the silicon oxide film; 
 forming a source electrode and a drain electrode on the channel; 
 forming a reaction field having a thickness on the silicon oxide film; 
 forming a barrier section formed of an insulating material on the silicon oxide film, the barrier section surrounding the reaction field and being thicker than the reaction field; and 
 forming a gate electrode on the barrier section, 
 wherein the source electrode and the drain electrode are arranged on a different place from the reaction field. 
 
     
     
       7. The method according to  claim 6 , wherein the drain electrode and the source electrode are formed on the surface of the silicon substrate on which the reaction field and the barrier section are formed. 
     
     
       8. The method according to  claim 6 , wherein the gate electrode is formed so as to surround the reaction field. 
     
     
       9. The method according to  claim 6 , wherein the barrier section is formed of silicon oxide.